BCR and primary central nervous system lymphoma: The B-cell antigen receptor complex-associated protein beta chain (CD79B) and myeloid differentiation factor 88 (MYD88) genes are frequently mutated in PCNSL, affecting the activation of the B-cell receptor (BCR) and the Toll-like receptor (TLR) signaling pathways, which in turn triggers the downstream NF-κB signaling pathway and promotes tumorigenesis (14).